Abusive gym teachers
I think when I was in middle school and high school, teachers who were too nasty for regular teaching and had a violent streak became gym teachers.
One of the nastiest I had was in middle school. The guy was the coach of the JV high school basketball team but he wasn't at the high school because he got kicked out over complaint of violence against a student. So, what did they do? they sent him to the middle school
and he still got to coach high school basketball. Even as horrible as middle school kids are, we knew not to mess with that guy. He didn't really speak, he just grunted and he always had a toothpick in his mouth. If any of us did anything wrong, we all ran laps all period. He actually liked to make us run laps all period because he would get to go inside and watch us out the window and not have to do anything.